Recent statistics from the National Cardiovascular Data Registry show that approximately 10% of our current percutaneous coronary interventions (PCIs) were performed for in-stent restenoses (ISR). Treatment of ISR with PCI can vary in complexity but can often be a challenging procedure as, generally, outcomes are worse than those compared to the PCI of de novo lesions [ ]. There are many interventional strategies to treat ISR lesions: conventional balloon angioplasty (BA), cutting or scoring balloon, drug-coated balloon (DCB), drug-eluting stent (DES), rotational atherectomy (RA), excimer laser coronary atherectomy (ELCA), lithotripsy, and vascular brachytherapy (VBT). For bare metal stent (BMS) ISR, standard therapies are DCB or DES implantation. The RIBS V randomized trial showed acceptable clinical outcomes for BMS-ISR in both the everolimus-eluting stent (EES) and DCB arms, with slightly better angiographic outcomes in the EES arm [ ]. For DES ISR, deploying another DES inside of the ISR lesion is one of the possible first-line treatments; DCB may be considered a next-line strategy. One meta-analysis demonstrated that EES was the most effective strategy for the treatment of DES ISR compared to BA, BMS, first-generation DES, EES, RA, and VBT [ ]. Before DES implantation or DCB inflation, of course, proper preparation of ISR lesions is absolutely necessary. This is most specifically because stent underexpansion and or undersizing are known to be key risk factors for adverse long-term outcomes [ , ].